In the computer arts there are many situations in which users are provided with very large numbers that users must recall. Such numbers include document file names, document version and date stamp values, and hash values. Such large numbers add to the blizzard of other large numbers that people are expected to memorize, including social security numbers, employee numbers, telephone numbers, badge numbers, combinations, zip codes, passwords, personal identifier numbers (PIN), etc. Studies have shown that most people have difficulty remembering numbers longer than four digits, yet the variety and quantities of long numbers and random letter combinations that people are expected to memorize (e.g., PINs) only seem to increase with each new technological innovation.
Another problem in the computer arts concerns tracking and distinguishing various versions of large documents, such as complex computer software programs. Small changes to such documents can be difficult to identify and yet may have significant impact on the usefulness of the document. Typically documents are saved under a single file name, with changes and subsequent versions saved to the same file name. Thus, a document's file name is not a reliable means for distinguishing different versions. Adding version numbers and time-stamps to documents and file names can be helpful, but are not fool proof, especially in cases where multiple people are working on “branches” of the same document. Also, users may forget version numbers and time stamps as, again, the complexity of such numerical data is difficult to remember.